Engines That Make 10,000 Horsepower

A look at the technology involved in Top Fuel drag racing, revealing some incredible performance facts and figures – powered by major sponsors’ money, computers, derring-do and sheer professionalism

You may never feel the need to perform a one-wheel burnout again…

SPACE-LAUNCH G-FORCES

We start with a couple of accelerative facts. Firstly, did you know a Top Fuel dragster will have hit 300mph before you finish reading this sentence? Or, imagine you’re racing your ‘06 C6 Corvette against a Top Fuel car over the quarter mile. You have the advantage of a flying start and after shifting up through the gears you’re able to blast across the startline, past the stationary fueler, at 200mph. At this moment, the dragster launches, and comes after you. Your foot is hard to the floor, but you hear an incredibly brutal whine searing your eardrums and within seconds the dragster has caught and passed you. No contest. You’ve lost. From a standing start, the fueler has covered the quarter mile in 4.5 seconds, with a terminal speed in excess of 300mph. It reached 100mph in less than one second and by the eighth mile, or 660ft, the dragster was doing around 270mph. Its average acceleration was about 3.4g, though in reaching 200mph well before half track, the initial figure was closer to 5.5g. This is greater than a space-shuttle launch at 3g. On the subject of g-forces, typical deceleration at the top end, courtesy of twin chutes, is a retina-detaching 5g, the condition that led to the retirement of the legendary “Big Daddy” Don Garlits from Top Fuel racing. The (backed up) National Hot Rod Association Top Fuel elapsed time record for the quarter mile was 4.428-seconds, set by Tony Schumacher at the Auto Club Finals in 2006. ( We say “was” because in the name of safety the NHRA and FIA Top Fuel cars now run over 1,000ft – 320ft less than a quarter of a mile. This means the car’s are now recording elapsed times in the three-second bracket, with terminal speeds of 320mph-plus). A year earlier, Tony attained the fastest-ever Top Fuel terminal speed at 337.58mph. To achieve these figures the engine has to peak at around 8,500rpm – a figure which comes from post-run data readouts because the cars have no rev counters. There’s no time to even glance at one.

THOUSANDS OF HORSES

Top Fuel dragsters no longer run the likes of ex-truck Dodge hemi engines rebuilt to racing spec. Nowadays you have to purchase 500-cubic-inches of scientifically-designed, aluminum-encased energy that will kick-out more horsepower than can be mustered in total by the first eight rows of NASCAR stockers at Daytona. Ten thousand horsepower — more than one thousand horses per cylinder. Wow, that’s a whole prairie of Mustangs! It’s said that a stock hemi engine would not produce sufficient power to drive the fueler’s 14-71 supercharger, which requires around 1,100hp, depending on the setup.

TWO GALLONS A SECOND? GULP!

Fuel consumption. Thought you wouldn’t ask. Under full throttle, a Top Fuel car consumes two Imperial gallons of 90 per cent nitro-methane per second. This is comparable with the fuel burn of a fully-loaded Boeing 747, which with its four turbofan engines on take-off power will gulp a couple of (Imperial) gallons of Jet-A1 every one-and-a-half seconds. Incidentally, jet fuel creates about four times the energy of nitro-methane, so that Jumbo’s “power pods” are pushing-out somewhere in the region of 32,000 shaft horsepower all together.

AN EARBASHING UNEQUALLED

We know rock concerts are noisy, perhaps treating us to 104 decibels of sound. Sitting 20ft from the edge of a NASCAR stock car race offers several hours of open-header V8 chorus putting out a constant 106dB. But neither example comes close to Top Fuel’s staccato 150dB. It might sound like music to your ears, but it’s actually physically damaging. For every three “extra” decibels, sound doubles. That explains why165-plus decibels equal total destruction of the eardrums. So, get those plugs in! They’ll bring the level down to a safe 20dB. Once again, Don Garlits knows the score. He says real fans don’t hear the fuelers with their ears, they hear them with their bones. “And their bones will still be shakin’ when they’re six feet under!” Talking about shaking, the NHRA once had seismologists out on the startline to record the effect of a pair of Top Fuelers launching. Did the earth move for them? How about a measurement of 2.3 on the Richter scale? So, not only can you hear those ground-pounding missiles with your bones, you can feel them with the soles of your feet.

TYRES THAT GROW, AND CHANGE GEAR

A dragster’s 17-inch-wide, 36-inch diameter, rear slicks grow taller by as much as 4-1/2 inches during a run due to centrifugal force; hardly surprising since they operate with a pressure of just 4-to-5psi, have to absorb around 4,500ft-lb of torque and will reach around 133 revolutions per second by the time the car goes through the timing traps at the end of the strip. The tyres’ growth also acts as a constantly-changing final drive ratio, in other words providing a higher ratio at the end of the run. The “rotational inertia” of the tyres delivers an enormous amount of down force on to the car. Because the wheel rim spins faster than the tyre, this causes the sidewall to wrinkle at the bottom. Once the slick “tread” reaches the rear part of the contact patch on the track, it speeds up to catch up with the rest of the wheel rim. This momentum causes great forces that are hugely responsible for the incredible launch-acceleration times. After that, acceleration is down to engine torque. All very complex to the uninitiated, but at least we can now understand why the slicks are screwed to the wheel rims!

WINGS AND THINGS

Three wings are better than one! Just ask the Red Baron. He got there first, and that’s what counts in drag racing too. We know dragster rear wings are there to keep the driving wheels in contact with the track, but the primary purpose of a front wing is to keep the car from pitching up and flipping over. Because rear wings are mounted as far aft as possible, there is a tendency for the front wheels to be lifted off the track surface due to weight transfer and the drag of the wing. The front wing’s downforce enables the driver to retain directional control. However, it’s not just a matter of adding wings and saying a prayer, the shape and structure of rear wings in particular — now mostly made of carbon fibre or Kevlar — is the result of some very sophisticated scientific calculation and research, including the involvement of NASA. Experiments on multi-element wings by the aviation industry many years ago proved they were more efficient at providing lift than single-element wings. Aircraft, of course, need lift to fly, but dragsters want to hug the track, or dig in. For this reason the dragster wing is mounted upside down, creating downforce or “negative lift.” The governing National Hot Rod Association has set rules and limitations that must be met with regard to the type, size and position of rear wings, which also must be locked in place so as to prevent any potentially-dangerous adjustment during a run. In simple terms, aerodynamics call for a wing providing maximum down force to be perhaps three feet wider than used, but the NHRA limits the permitted surface area. The main reason the span is kept to the width of the car or less is because if any part of the car crosses the centerline, the driver is disqualified. State-of-the-art Top Fuel dragster wings produce some eight tons of down force 330mph, which means in theory you could run the car upside down in a tunnel — assuming you could get it up there in the first place! In the same way “winglets” on modern passenger airliners enable them to improve fuel economy and extend their range by tidying-up the disruptive airflow found at the end of a conventional wing, the addition of endplates on dragster rear wings produces vast improvements in the down-force-to-drag ratio. Perfecting the exact shape of the endplates came about largely due to the involvement and very serious analysis by a NASA flight institute. In conclusion, Top Fuel racing obviously cannot be described as “Brute force and bloody ignorance.” In truth, it’s almost rocket science.